<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="jquery.min.js"></script>
    <style>
        div {
            width: 200px;
            height: 200px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div></div>
    <script>
        //1. $是jquery的别称
        /*jQuery(function () {
            window.alert(123);
        });*/

        $(function () {
            window.alert(321);
            //$(`div`).hide();
            jQuery(`div`).hide();
        });
    </script>
</body>
</html>